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From "Xiao Chen (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HADOOP-15550) Avoid static initialization of ObjectMappers
Date Fri, 22 Jun 2018 20:06:00 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-15550?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16520740#comment-16520740

Xiao Chen commented on HADOOP-15550:

Thanks Todd and Steve. Latest patch looks great!
Sorry for the nit, {{WRITER}} and {{MAP_READER}} could be final (seem to recall checkstyle
should complain that, not sure why it doesn't this time). +1 from me pending that.

> Avoid static initialization of ObjectMappers
> --------------------------------------------
>                 Key: HADOOP-15550
>                 URL: https://issues.apache.org/jira/browse/HADOOP-15550
>             Project: Hadoop Common
>          Issue Type: Bug
>          Components: performance
>    Affects Versions: 3.2.0
>            Reporter: Todd Lipcon
>            Assignee: Todd Lipcon
>            Priority: Minor
>         Attachments: hadoop-15550.txt, hadoop-15550.txt, hadoop-15550.txt, hadoop-15550.txt
> Various classes statically initialize an ObjectMapper READER instance. This ends up doing
a bunch of class-loading of Jackson libraries that can add up to a fair amount of CPU, even
if the reader ends up not being used. This is particularly the case with WebHdfsFileSystem,
which is class-loaded by a serviceloader even when unused in a particular job. We should lazy-init
these members instead of doing so as a static class member.

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